The cost of an Aircraft on Ground (AOG), for whatever reason, is very significant and the airline operators look to the manufacturers where possible to reduce the impact of this by planned maintenance and/or clearance for further flight until the next scheduled maintenance point can be reached. However, there are events where planning cannot help. One such event is a “Hard Landing”.
A “Hard Landing” occurs when, for whatever reason, the certified landing parameters are exceeded. This would normally be reported by the aircraft pilot and subsequently confirmed by inspection of the confirmed by inspection of the airframe structure and information extracted from the Digital Flight Data Recorder (DFDR). The problem lies in the time taken to analyse data confirm whether the event was truly a “Hard Landing” or not. This analysis can sometimes take up to 3 weeks to conclude and is not often tolerated by the aircraft operator.
U.S. Pat. No. 4,392,623 describes a fused connection adapted to fail under different overloads acting in different directions. The objective is to protect the fuel tank (primary wing structure) from rupture resulting from landing gear overload in either the vertical or horizontal directions.
U.S. Pat. No. 5,927,646 describes an energy absorbing landing gear/tail skid including means for indicating the magnitude of impact loads. Impact loads effect plastic deformation of the device, and an elongate stem protrudes beyond a reference surface to provide a visual indication that the magnitude of impact loads has reached a threshold value.